Through supervision system



6, 1940- H. w. ULRICH 2,210,739

THROUGH SUPERVISION SYSTEM Filed Nov. 25, 1938 2 Sheets-Sheet 1 IIHI-NIGHT AL ARM RELEASE INVENTOR HWULR/CH BY A Woe/DEV Aug. 6, 1940. H. w.ULRICH 2,210,739

THROUGH SUPERVISION SYSTEM Filed Nov. 25, 1958 ZSheets-Sheet 2 MEL FIG 2Ti v A TTORNE V Patented Aug. 6, 1940 UNITED STATES 2,210,739 THRQUGHSUPERVISION SYSTEM Horace W. Ulrich, Newark, N. J., assignor to BellTelephone Laboratories, Incorporated, New York, N. Y., a corporation ofNew York Application November 25, 1938, Serial No. 242,151

8 Claims.

This invention relates to telephone systems and more particularly totwo-way trunk circuits between two exchanges, as between a toll officeand a tributary central office serving both local 5 battery (magneto)and common battery subscribers.

An object of the invention is to provide through supervision over thetrunk to the toll operator between a calling common battery subscriber lserved by the tributary office and the toll office,

regardless of the direction of the call.

A feature of the invention whereby the foregoing object is attainedresides in terminating the trunk at the tributary exchange in a jack andso arranging the circuits of the trunk and the tributary ofiice cordcircuit that when both ends of the trunk are connected, a tributarycommon battery subscriber will, when connected to the trunk, control thesupervision to the toll operator.

Other features of the invention will appear and be understood from thefollowing description and accompanying drawings of which Fig. 1illustrates a common battery subscriber A adapted to be connected by acord circuit SC, of a so-called toll tributary exchange, to a twowaytrunk line L extending to a so-called toll center; and

Fig. 2 shows the toll center end of the trunk line L and a toll cordcircuit TC adapted to extend the trunk line L to a subscriber B.

A description of the operation of the circuit of the invention will nowbe given first assuming that the subscriber A (Fig. 1) has placed a callfor a subscriber such as B (Fig. 2) which subscriber is reached over thetrunk line L.

When subscriber A lifts his receiver to initiate a call, his line lamp(not shown) is lighted in the usual manner. The operator inserts plug 2of cord circuit SC in jack I of the subscribers line, whereuponanswering sleeve relay 3 of the cord operates from ground on the sleeveof jack I in series with the supervisory lamp 4. Relay 3 closes itsright-hand front contact thereby connecting ground and battery throughthe upper and lower windings of supervisory relay 5, to the subscribersline which is now closed due to receiver having been removed from theswitchhook, whereupon relay operates. The operation of relay 3 alsoopens its outer right back contact thereby disconnecting the middlewinding of relay 5, which winding is normally in series with the upperand lower windings across the cord. Operation of relay 5 connects groundat its inner lowermost front contact to short-circuit supervisory lamp 4and prevents it from lighting at this time. Relay 5 also closes itsinner lower front contact thereby connecting ground, through highresistance 6, to the sleeve of the front or calling plug 1. The value ofresistance 6 is such, however, that the front or calling supervisoryrelay 48 is not operated at this time nor is lamp 49 lighted.

When the operator inserts plug 1 into jack 8 of the trunk line L, theauxiliary jack spring contacts 9 are immediately closed therebycompleting an obvious circuit to operate the trunk sleeve relay II)which operates and closes its contacts II, I2, I3 and I4. The closure ofcontact I I lights the busy lamp I5, and multiples thereof, and closureof contact I2 connects relay I6 to the sleeve of jack 8 which is nowconnected to ground in the cord by Way of resistance 6 and the lowerfront contact of relay 5. Relay I6 which is ultrasensitive operates inseries with the high resistance.

When the tip and ring contacts of the plug 1 are in engagement with thecorresponding springs of the jack 8, relay 50 operates in a circuitincluding battery, contact SI of relay 47, upper left winding ofrepeating coil 22, tip contact of the jack and plug, all three windingsof relay 50 which are connected in series over contact 52 of relay 48,ring contact of the plug and jack, lower winding of repeating coil 22and resistance 53 to ground at contact 54 of relay 41. Relay 5!! inoperating closes its lowermost contact and connects ground, over theright-hand back contact of relay 48 to light lamp 55 in the cordcircuit.

Closure of contact I3 of relay I6 connects ground to relay I'l over apath including contacts I8 of relay I9. While relay I1 operatesimmediately following the closure of contact I 3, I

in the path just traced, which includes contact iii of relay I9, theoperation of relay I6 and the consequent closure of its left frontcontact, completesa short circuit around contact i8 which includescontact 20 of relay 86 so that a subsequent operation of relay I9 willnot release relay I'I. When relay Il operates due to operation of relayIll, it short-circuits the high resistance (lower) winding of thepolarized relay 2| which is bridged across the condenser in theright-hand side of transformer 22. This reduction in resistance inbridge of the line causes marginal relay 23 (Fig. 2) at the toll ofiic'eto operate which in turn closes the following circuit: battery, wind ingof relay 24, front contact of relay 23, contact 25 of relay 24, contact26 of relay 21, and both windings of relay 28 to ground through highresistance 29. The left-hand winding of relay 23 is of low resistancebut its right-hand winding is sufficiently high so that relay 24 can notoperate in series therewith. Relay 28, however, is sufiicientlysensitive to operate in this circuit, whereupon it releases the normallyoperated relay 30 which closes its right-hand back contact to operatethe night alarm relay 3I which looks up the relay 32 under the controlof key 80. Relay 3| operating, closes a circuit to energize the nightalarm buzzer 33. Release of relay 30 also tact 36 of relay 2 closes itsleft-hand contact which short-circuits the right-hand high resistancewinding of relay 28 and the high resistance 29 thereby lowering theresistance of the previously traced circuit for relay 24 to a pointWhere it can operate. Operation of relay 24 closes its contacts 34, 35,35 and El. The closure of contacts 34 connects battery, over contact 38of relay 39 to the sleeve of jack it! and multiples thereof to hold theline busy to calls in the opposite direction. Closure of contact 35 andthe subsequent opening of contact 25 looks relay 24, operated under thecontrol of relay 23, and opens the previously traced circuit foroperating relay 28 which thereupon releases thereby permitting relay 30to reoperate. Closure of contact '36 lights the line lamp 4i andmultiples thereof over the left back contact of relay 2'! and closure ofcontact 3'! lights the busy lamp 42 and its multiple.

When the toll operator answers by inserting plug 33 jack as, relay 3%!is operated due to the closure of auxiliary contact 44, the circuitincluding normally closed back contact 45 of relay 5. Relay 39 inoperating operates relay 27, looks up over its left-hand contact andcon- Relay 35; opens its contact 38 thereby disconnecting the busypotential applied over contact as of relay 24 as the sleeve of plug A3now supplies such a busy potential to the multiples of jack it Further,relay 39 in operating reverses at its left-hand contact the connectionof relay 23, and its battery supply, to the line whereupon polarizedrelay 2% at the tributary oflice (Fig. l) which up to this time has beenreleased due to the direction of the current flowing in its winding, nowoperates, and in turn operates relay ll. Relay ll in operating opens itscontacts 5! and 54 thereby disconnecting battery and ground from thetransformer 22 and thence to the line which causes relay '50 of the cordto release thereby extinguishing lamp 55. Relay ll also closes itscontact 56 thereby closing a circuit to operate relay l9 which can betraced from battery, right-hand winding of relay I9, contact 5% of relayll, contact 57 of relay l9, and contact i of'relay H] to ground. Relayl9 operates and locks itself at contacts 58 under control of contact 58of relay ll which in turn is controlled from the distant 'toll office.Relay l9 also closes its left contact 59 thereby completing a secondlocking circuit for' itself including its left-hand winding which can betraced from bottery, left winding, contact 59 of relay l9 and contact S3of relay in to ground. Relay l0 being under control of the plug '5 ofthe tributory ofiice, it will be noticed that relay I9 is now heldoperated until both ends of the trunk line become idle.

When relay l9 operated it opened its contact is over which relay l! wasfirst operated. Relay 21', however, does not release as it is still heldoperated over a path in parallel with contact I8 which is due to theleft-hand front contact of relay :5 and contact as of relay 86. It willnow be noted that control of relay I"! which in turn controlssupervision over the lines to the distant toll oflice is now undercontrol of both the plug 7, i. e. its controlled relay Ill, but alsounder control of the calling supervisory relay 5, which, while operatedmaintains ground on the sleeve of the plug '5 and jack 3 of the trunkline to hold relay it operated. It will therefore be obvious that duringthe existence of the connection to the trunk line, any movement of thecalling subscribers switchhook will release relay 5, in turn releasingrelay is which in its turn will release relay H. The release of relay llwill reconnect the lower high resistance winding of relay 2| in thebridge across the line thereby causing relay 23 at the toll ofnce torelease. The release of relay 23 releases relay 2t which closes itscontact Ell thereby grounding the sleeve of jack 4i] in a circuitincluding contacts 6! of relay 39.

ing coil it, thereby preventing ringing current 2 from. passing throughthe repeating coils to the lines. At contacts 39, relay 36 connectsground to hold relay 2'? operated when relay 39 releases, to be laterreferred to, and at contacts 58 it connects ground to the sleeve of jackMl, to keep supervisory lamp 52 lighted as it is assumed that thecalling subscriber A has disconnected and consequently relay 24 isreleased as previously mentioned.

Operation of relay as also opens its contact and immediately closescontact H and also closes contact 72 thereby placing relay 39 undercontrol of interrupter I which alternately disconnects and connectsground thereto thereby causing that relay to alternately release andreoperate. The release of relay 39 reverses the current flowing backover the trunk and releases relay 2! which in turn releases relay 4;!which reconnects battery and ground at the mid point .of the left handside of repeating coil 22 which causes supervisory relay 56 in the cordcircuit to operate to light supervisory lamp 55. As the interrupter Ialternately releases and operates relay 3? the lamp in the cord circuitis flashed as long as the toll operator continues to ring.

In case it is desired to retain supervision at the tributarycffice, i.e. not transmit through supervision to the toll center, the tributaryoperator will make connection to the trunk line by way of the so-callcdplug supervision, jack 53,'whereupon relay t l instead of relay IEoperates. Under this condition the ground on the sleeve of plug 1 isineffective as the sleeve of jack 53 is not connected to relay [8. Relay84 closes its right-hand contact, thereby lighting the busy lamp l5 andits multiples and operates relay H which short-circuits the highresistance winding of relay 2| thereby operating relay 23 at the tollofiice as before to light the line lamp 4|.

When the toll operator answers, relay 39 operates as before described toreverse the line battery and causes relay 2! at the tributary office tooperate which operates relay cl. Relay 4'! disconnects at contacts 5iand 54, battery and ground at the mid-point of the left-hand winding ofrepeating coil 22 thereby releasing relay 5!) which extinguishes lamp 55in the cord circuit. The closure of contact 55 of relay 41 operatesrelay It in a circuit from ground, contact '13 of relay 64, outer rightback contact of relay IE), not now operated, contact 57 of relay i9,contact 58 of relay 47 and right winding of relay l9. Relay I9 closesits contact '58 thereby locking it self operated under control of relay57, i. e.

under contro1 of the distant toll ofiice, but does eration at this time.

not find a locking ground for its left-handwinding under control of thetributary cord SC as relay [0, which supplied this ground when jack 8was in use, is not now operated.

As the sleeve or jack 63 is not connected to relay [6, as is the sleeveof jack l8, movement of the calling subscribers switchhook does notaffect relay I7 and hence supervision is restricted to the tributarycord circuit SC and is received on supervisory lamp 4 in theusual'manner only. The supervisory lamp 62 in the toll ofiice remainingdark until the tributary operator disconnects from the jack 63 whereuponrelays 13 and I! release in turn releasing relays 23 and 24 which nowlight lamp 62.

Non-through supervision jack 63 is also used for connecting callingmagneto (local battery) stations to this trunk line. In this case due tothe fact that magneto station line circuits do not have the jack sleevegrounded, the answering cord sleeve relay 3 does not operate at any timeand the answering cord supervisory relay 5 only in response to ringingcurrent occasioned by the subscriber turning the crank of the telephoneset generator. Under this condition the tributary operator receivessupervisory signals from both ends of the cord on the lamp 55.

Now let us assume a call in the opposite direcitno, i. e. a call fromthe toll center (Fig. 2) to a common'battery subscriber A which isreached through the tributary office (Fig, 1)

When the toll operator inserts plug 43 in jack 4!], relay 39 operatesfrom grounded contact 44 of the jack which reverses the battery suppliedtothe line and causes polarized relay 2| of the tributary end of thetrunk to operate.

Relay 39 also closes its inner right contact to operate relay 2'! and byclosing contact 6! connects ground, supplied over contact 60 of relay24, to the sleeve of the jack 4!! and plug 43 which causes cordsupervisory lamp 62 to light and sleeve relay (4 to operate. Operationof relay 2! closes its inner right contact to light the busy lamp 42 andmultiples thereof. Operation of relay 2! at the tributary end of thetrunk operates relay 4'! which causes the delayed operation of relay l9as follows: closure of contact 55 of relay 41, operates relays in thefollowing circuit; battery, right winding of relay 19, contacts 56 ofrelay 41, contacts 51 of relay l9, outer right back contact of relayIll, back contact of relay 64, both windings of relay 15, and highresistance 15 to ground. Relay 15 operates in this circuit but due tothe high resistance of the right-hand winding of relay 15 and resistance16, relay l9 does not receive suflicient current to cause its op-Operation of relay "(5 opens its contacts and permits normally operatedslow release relay 1'! to deenergize. Vvhen relay TI releases it closesits right-hand contact and aperates relay 18 which closes a circuit tooperate .the night alarm buzzer 19 which locks up under control of arelease key. The closure of the left hand contacts of relay Hshort-circuits the righthand winding of relay 15 thereby decreasing theresistance of the circuit including relay l9, which relay now operatesand locks up the ground at its contact'58 under control of contact 56 ofrelay 41. The opening of contacts 51 of relay l9 breaks the circuitthrough relay 15 which releases and permits relay 1'! to reoperate.Operation of relay 4'! also closes its contacts ill and 82 which lightthe line lamp 83 and busy lamp l5 including multiples thereof. All callsfrom the toll center are answered in the through supervision jack 8 and,consequently when the operator at the tributary oflice notes the lightedline lamp 83 she inserts plug 1 in jack 8. Due to the fact that relay 41is operated at this time, battery and ground are disconnected from thetrunk and contacts 5| and 54 and therefore supervisory relay does notoperate and the supervisory lamp remains dark.

When the plug is inserted in jack 8, auxiliary contacts 9 are closedthereby operating relay In which at its contact maintains the busy lampl5 lighted independent of the circuit previously traced which wascontrolled by contact 82 of relay 41. Closure of contact l2 of relay I 0connects relay Hi to the sleeve of jack 8 in readiness for operation, ifand when a called common battery subscriber is connected to the otherend of the cord and the subscriber answers. ,When this occurs relay l6operates in series with high resistance 6 thereby closing its frontcontact and closing a circuit to operate relay I! which can be tracedfrom ground, contact [3 of relay In, front contact of relay It, contact20 of relay 86, and windings of relay I! to battery. Relay l1 operatesand short-circuits the high resistance winding of relay 2! and causesrelay 23 of the toll center to operate which in turn operates relay 24thereby locking itself under control of relay 23. Relay 2'! is also heldoperated at contact. 36 of relay 24 under control of the tributaryoflice and independent of the holding effect exercised by the relay 39.Operation of relay 24 also opens its contact thereby removing the groundfrom the sleeve of the jack 40 and extinguishing the supervisory lamp 62as an indication that the called subscriber has answered. Any furthermovement of the called subscribers switchhook will release relay 24 toreapply grounded'contact 60 to the sleeve of the jack to relight thesupervisory lamp 62.

In case the call from the toll center was for a magneto subscriber atthe tributary ofiice, which would be answered in the same manner asbefore by the tributary operator, the response of the called subscriberwill not operate relay [6 due to the fact that supervisory relay 5 isnot affected by a magneto subscribers switchhook and consequently it isincumbent on the tributary operator, in such cases, to manually relaythe subscriber's answer to the toll operator by op erating the key 84.When this key is operated, it completes a circuit to cause operation ofrelay I! which can be traced from ground, contacts l3 of relay IIJ,normal back contact of relay I6, contacts of key 84 and winding of relay86 to battery.

Relay 85 closes its left front contacts thereby connecting ground atcontact I? of relay [0 to relay I! which operates and extinguishes thetoll cord supervisory lamp 62 as previously described. Re-

lay BB locks up at its front contact under control of contact 56 ofrelay 41. This locking circuit can be traced from battery, winding ofrelay 86, contacts 85 of relay 59, contacts 56 of relay 4?, and contacts58 of relay lfito ground. This locked condition of relay 86 maintainsrelay ll operated and the toll cord supervisory lamp 62 extinguishedunder control of the plug 1 of jack 8. When the conversation iscompleted, the tributary operator removes plug 7 from jack 8 therebyreleasing relay Ill which releases relay [1 and relights the toll cordsupervisory lamp 62. Release of the trunk by the toll operator restoresthe circuit to normal thereby releasing relay 39 which reverses the linebattery to release relay 21 which in turn releases relays 41, IS and 86.

What is claimed is:

1. In a telephone system, a first operators position, a subscribers lineterminating thereat, a trunk line also terminating at said position in ajack having a sleeve terminal, a cord circuit at said first position forinterconnecting said line and trunk and having a sleeve conductorcooperating with said jack sleeve when said cord and trunk areconnected, a second operators position terminating the other end of thetrunk, a supervisory relay in said first position cord circuitcontrolled over said subscribers line, a link circuit at said secondposition adapted to be con nected to the trunk, supervisory means insaid link circuit, relay means in said trunk at the second position endthereof controlled over the trunk for controlling said supervisory meanswhen said trunk and link are connected, means in the first position endof the trunk for transmitting signals over said trunk to operate saidrelay means at the other end, means responsive to connection of saidfirst position cord circuit to said trunk jack to operate said signaltransmitting means, locking relay means in the trunk at the firstposition operated when the distant link circuit is connected to thetrunk, and thereafter held operated until both ends of the trunk aredisconnected, for transferring control of said signaling means from saidmeans responsive to connection of the cord to the trunk jack to saidsupervisory relay over said connected sleeve conductors of the trunk andcord.

2. In a telephone system, a first operators position, a subscribersstation line terminating thereat, a trunk line also terminating at saidposition, a cord circuit at said first position for interconnectingsaidline and trunk, a supervisory relay in said first position cordcircuit controlled over said line, a second operators positionterminating the other end of said trunk, a cord circuit tliereat adaptedto be connected to the trunk, means in said trunk responsive toconnection of one end of said first position cord circuit to the trunkto transmit a signal thereover independent of the cord supervisoryrelay, locking means in the trunk operated when the second position cordcircuit is connected to the trunk following the connection of the firstposition cord circuit thereto, and thereafter held operated untilbothcords are disconnected from the trunk, for transferring control of saidfirst means to the supervisory relay in the first position cord circuit,said control being exercised over the connected sleeve circuit of thecord and trunk.

3. In a telephone system, a first operators position, a subscribersstation line terminating thereat, a second operators position, a trunkline extending between said positions, a cord circuit at the firstposition for connecting the subscribers line to the trunk and includingsupervisory means controlled over the subscribers line, a cord circuitat the second position adapted to be connected to the trunk andincluding a supervisory signal device, means controlled over said trunkfor controlling said device, and other means in said trunk at the firstposition controlled over the sleeve circuit of the cord by saidsupervisory means for controlling said means to control said device.

4. In a telephone system, a first operators position, a subscribersstation line and a trunk line terminating thereat, a cord circuit atsaid position for interconnecting said trunk and subscribers line, asecond operators position termimating the other end of said trunk line,a cord. circuit at said second position including a supervisory signaldevice, means in said trunk for controlling said signal device, asupervisory relay in said first position cord circuit controlled by thesubscribers station switchhook, and means, including the interconnectedsleeve conductors of said first position cord and trunk, controlled bysaid supervisory relay, for controlling the means in said trunk.

5. In a telephone system, a first switchboard, a subscribers stationline terminating at said switchboard, a toll switchboard, an automaticsignaling trunk extending between said switchboards, a cord circuit atthe first switchboard adapted to connect said subscribers line to thetrunk line, a cord circuit, including a supervisory signal device, atthe toll switchboard, adapted to be connected to the trunk line, meansin said trunk for controlling said supervisory signal when theassociated cord circuit is connected to the trunk, supervisory meansassociated with the cord circuit at the first switchboard responsive toremoval of the subscribers station receiver while the cord circuit isconnected to the line, and means including the sleeve conductors of thecord at the first switchboard, effective when said supervisory meansresponds, to control said trunk means.

6. In a telephone system, a first operators position, a subscribers lineterminating thereat, a trunk line also terminating thereat, a cordcircuit thereat for interconnecting said line and trunk, a supervisoryrelay for said cord circuit controlled over the subscribers line, sleeveconductors for said cord and trunk arranged to be interconnected whensaid cord and trunk are connected, a second position terminating theother end of the trunk, a link circuit at the second position forconnecting to the trunk, a supervisory signal device associated withsaid link circuit, and means in said trunk controlled by saidsupervisory relay over the connected sleeve conductors of the cord andtrunk for controlling the signal device in the link circuit.

'7. In a telephone system, a first operators position, a subscribersline terminating thereat, a

trunk line also terminating thereat, a cord circuit thereat forinterconnecting said line and trunk, a supervisory relay for said cordcircuit controlled over the subscribers line, sleeve conductors for saidcord and trunk arranged to be interconnected when said cord and trunkare connected, a second position terminating the other end of the trunk,a link circuit at the second position for connecting to the trunk, aline relay associated with the trunk at the second position, meansresponsive to connection of the first position 'cord to the trunk foroperating said line relay independent of the condition oi the other endof the cord and means responsive to the connection of said link circuitto the trunk to trans-

